The field of the disclosure generally relates to turbine engines, and more specifically to systems and methods for dynamically sealing a turbine engine.
A turbine engine generally includes a rotor assembly and a stator assembly. At least some known rotor assemblies include at least a disk coupled to a plurality of rotor blades, sometimes referred to as airfoils, that extend radially outward from the disk to a tip. In known turbine engines, the rotor blades are circumferentially bound by a casing that defines an interior surface of the turbine assembly. In operation a fluid, such as, air, steam, or combustion gases, for example, interact with the rotor blades to produce useful work. For example, the turbine engine may power a compressor, an electrical generator, and/or an electrical load.
Further, in known turbines, an area between the tip of the rotor blades and the casing, referred to as a clearance gap, may enable the fluid to undesirably flow around the rotor blades without interacting with them. Fluid flowing through the clearance gap does not produce any useful work, and as such, the clearance gap is an important characteristic in determining the efficiency of a turbine engine. More specifically, an inverse relationship exists between the size of the clearance gap and the efficiency of the turbine engine. For example, an engine with a relatively large clearance gap is generally less efficient, while an engine with a relatively small clearance gap is generally more efficient. As such, at least some known systems position a seal between the casing and the tip of the rotor blades during manufacturing, the seal decreasing the size of the clearance gap to improve turbine engine efficiency.
However, turbine engines do not have a static clearance gap at all stages of operation. More specifically, the amount of clearance associated with known turbine engines may fluctuate based on the operating condition associated with the turbine engine. For example, the clearance gap may change between start-up, idling, steady-state, shutdown, and transient operations due to rotor blade growth, for example. If the size of the clearance gap is manufactured too tightly, the rotor blades may rub against the casing and/or against the seal during various operating conditions, which may damage the engine and/or decrease efficiency. As such, known turbines and seals are typically manufactured with sufficient clearance to accommodate for the maximum extension of the rotor blades, including during various turbine operations.
In addition, in known turbines, replacing damaged seals may be an expensive and time-consuming endeavor that requires the turbine to be non-operational and/or at least partially disassembled.